A practical reference on circular dichroism: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-04-23 and is reviewed periodically as new material appears.
The compound first appeared in the scientific literature as an investigational agent for type 2 diabetes. Clinical development proceeded through phase 1, phase 2, and phase 3 programs that measured glycemic control as a primary endpoint while recording body weight as a secondary outcome. Regulatory approval in the United States followed in 2022 for glycemic control, and a separate indication for chronic weight management was added later. Subsequent trials have examined cardiovascular outcomes in adults with elevated cardiovascular risk. Debates continue over how much of the observed effect derives from each receptor arm.
Structural work on the molecule centers on a C20 fatty diacid moiety attached through a linker to the peptide backbone. This side chain promotes reversible binding to serum albumin, which slows renal clearance and supports a prolonged action profile. The peptide backbone incorporates aminoisobutyric acid substitutions that limit recognition by digestive enzymes. Together these modifications produce a molecule that is stable enough for subcutaneous delivery but still dependent on careful manufacturing control. Analytical characterization of the active pharmaceutical ingredient typically follows the conventions used for other synthetic peptides.
质量控制环节关注外观、含量、纯度、有关物质、水分与微生物限度等项目。检测结果需要有对照品和系统适用性数据支持，单次测定不足以判定批次的稳定性。实验室之间方法转移时，色谱柱品牌与梯度差异常导致保留时间漂移，因此方法验证十分必要。
固体状态的 tirzepatide 通常以冻干粉形式保存，推荐在低温、避光、干燥条件下存放，常见区间为 2 至 8 摄氏度，长期保存可考虑更低温度并避免反复冻融。冻融循环会导致肽链聚集或析出，从而影响后续定量结果。容器密封性与湿度控制同样是稳定性研究中反复强调的因素。
溶解操作一般使用注射用水或适宜的水性缓冲液，必要时加入少量助溶剂以改善溶解速度，但应避免剧烈涡旋振荡，因为剪切力可能促进聚集。配制后的溶液在冷藏条件下的稳定时间通常短于固体形态，具体时限取决于浓度、缓冲体系与容器材质。是否加入防腐成分，则取决于用途是否为多次取样。
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | Dual incretin receptor agonist |
| Amino acid count | 39 residues | Includes non-natural residues |
| Approximate mass | 4.8 kDa | Reported values vary slightly by source |
| Fatty acid component | C20 diacid | Supports albumin binding |
| First US approval | 2022 | Glycemic indication, weight management followed |
脂肪酸侧链的存在使该肽与血浆白蛋白结合能力增强，从而延长循环半衰期，支持每周一次给药的用药间隔。白蛋白结合同时改变组织分布特征，减慢肾脏清除速度。该设计思路在多种长效肽类药物中被反复采用，属于既定的药代动力学策略。
该化合物的名称与结构由国际非专利名称体系统一维持，不同文献中出现的同义写法主要在拼写顺序或盐形式描述上不同。研究者通常通过受体结合实验、细胞内环磷酸腺苷积累测定以及动物模型来确认其双激动活性。相当一部分分子层面的细节——例如两条受体通路之间的信号交叉作用——尚处于开放问题状态。
当前公开资料把 tirzepatide 归为肠促胰素类受体双重激动剂。它并非激素天然变体，而是经过序列改造的工程化肽。其分子量、等电点与疏水性等基础参数已在药典和化学数据库中收录，可作为分析检测和质量研究的参照。
Routine characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity assessment, usually with ultraviolet detection near 214 nanometers. Intact mass measurement by liquid chromatography coupled to mass spectrometry confirms molecular identity against a theoretical value. Sequence-level confirmation uses enzymatic digestion followed by tandem mass spectrometry, an approach known as peptide mapping. Amino acid analysis gives an independent check on composition. Circular dichroism spectra are used to estimate helical content in aqueous buffer.
Stability depends strongly on physical form. The dry powder is generally regarded as stable for extended periods when held at or below minus twenty degrees Celsius in a sealed, desiccated container. In solution, degradation pathways include deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation. Reaction rates for these pathways rise with temperature. Repeated freezing and thawing of solutions promotes aggregation, and light exposure can accelerate some oxidative changes. Buffer composition and pH influence which pathway dominates at a given temperature.
The Inner London Education Authority (ILEA) was the local education authority for the City of London and the 12 Inner London boroughs from 1965 until its abolition in 1990. From 1965 to 1986 it was an ad hoc committee of the Greater London Council; on 1 April 1986 it was reconstituted as a directly elected body corporate.
In 1907, American tea merchant Thomas Sullivan began distributing samples of his tea in small bags of silk with a drawstring. Consumers noticed they could simply leave the tea in the bag and reuse it with fresh tea. However, the potential of this distribution and packaging method would not be fully realised until later. During World War II, tea was rationed in the United Kingdom. In 1953, after rationing in the UK ended, Yorkshire-based tea manufacturer Tetley launched the tea bag in the UK, and it was an immediate success. The "pyramid tea bag" (or sachet), introduced by Lipton and PG Tips/Scottish Blend in 1996, attempts to address one of the connoisseurs' arguments against paper tea bags by way of its three-dimensional tetrahedron shape, which allows more room for tea leaves to expand while steeping. However, some types of pyramid tea bags have been criticised as being environmentally unfriendly, since their synthetic material is not as biodegradable as loose tea leaves and paper tea bags.
During transport water needs to be maintained to a high quality, with regulated temperature, sufficient oxygen and minimal waste products. In some cases anaesthetics may be used in small doses to calm fish before transport. Aquaculture is sometimes part of an environmental rehabilitation program or as an aid in conserving endangered species.
Sources: en.wikipedia.org
== Mechanism of resistance == Streptogramin resistance is mediated through enzymatic drug inactivation, efflux or active transport of drug out of the cell, and most commonly, conformational alterations in ribosomal target binding sites. Enzymatic drug inactivation may occur in staphylococcal and enterococcal species through production of dalfopristin-inactivating acetyltransferase or quinupristin-inactivating hydrolase. Efflux or active transport of the drug may occur in coagulase-negative staphylococci and Enterococcus faecium. Constitutive ribosome modification has been seen in staphylococci with resistance seen in quinupristin only. While resistance to dalfopristin may be conferred via a single point of mutation, quinupristin/dalfopristin offers the benefit of requiring multiple points of mutation targeting both dalfopristin and quinupristin components to confer drug resistance. Comparatively, only 2-5% of staphylococcal isolates collected in France show resistance to a related streptogramin, pristinamycin, in over 35 years of use.
In September 1981, shortly after Mahathir assumed office as prime minister, the country carried out the "Dawn Raid", a calculated operation orchestrated by Permodalan Nasional Berhad (PNB) to regain majority ownership of Guthrie, one of the largest British-owned plantation companies at the time. This move symbolized a broader effort under Mahathir's leadership to reduce foreign dominance over Malaysia's economy and reclaim control of national assets. A month after the Dawn Raid, Mahathir introduced the "Buy British Last" (BBL) policy, which lasted from October 1981 to March 1983. The reason for this policy was rooted in several grievances with Britain. Britain's decision to abolish tuition fee subsidies for Commonwealth students placed a heavy financial burden on Malaysia, which had to cover the increased costs for approximately 17,000 Malaysian students studying in the UK. Additionally, British media criticism of Malaysia's internal policies further strained relations. The BBL policy, which directed government ministries and agencies to deprioritize British goods and services, significantly affected Britain, causing estimated losses of between £15.5 million and £50 million in the early months. This eventually led to negotiations, culminating in Mahathir and British Prime Minister Margaret Thatcher meeting in 1983 to resolve the tensions and end the policy. Mahathir later recalled persuading Thatcher that raising tuition fees was a mistake, leading Thatcher to introduce scholarships for Malaysian students.
== Life cycle == Spawning of northeastern Atlantic cod occurs between January and April (March and April are the peak months), at a depth of 200 metres (660 ft) in specific spawning grounds at water temperatures between 4 and 6 °C (39 and 43 °F). Around the UK, the major spawning grounds are in the middle to southern North Sea, the start of the Bristol Channel (north of Newquay), the Irish Channel (both east and west of the Isle of Man), around Stornoway, and east of Helmsdale. Prespawning courtship involves fin displays and male grunting, which leads to pairing. The male inverts himself beneath the female, and the pair swim in circles while spawning. The eggs are planktonic and hatch between eight and 23 days, with larva reaching 4 millimetres (5⁄32 inch) in length. This planktonic phase lasts some ten weeks, enabling the young cod to increase its body weight by 40-fold, and growing to about 2 cm (3⁄4 in). The young cod then move to the seabed and change their diet to small benthic crustaceans, such as isopods and small crabs. They increase in size to 8 cm (3 in) in the first six months, 14–18 cm (5+1⁄2–7 in) by the end of their first year, and to 25–35 cm (10–14 in) by the end of the second. Growth tends to be less at higher latitudes. Cod reach maturity at about 50 cm (20 in) at about 3 to 4 years of age. Changes in growth rate over decades of particular stocks have been reported, current eastern Baltic cod shows the lowest growth observed since 1955.
Sources: en.wikipedia.org
It activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor. This dual activity separates it from agents that act on only one of the two receptors. The relative contribution of each receptor to clinical effects remains an open area of study.
United States approval for type 2 diabetes was granted in 2022, and a chronic weight management indication was added later. Approval timelines differ across other jurisdictions. Earlier human data came from phase 1 and phase 2 trials published before those decisions.
Native hormones are short-lived peptides that enzymes degrade within minutes. Tirzepatide carries non-natural residues and a fatty acid chain that resist this breakdown and extend circulation time. The result is a longer interval between administrations than the natural hormones could support.
建议在低温、避光、干燥环境中密封保存，常见条件为 2 至 8 摄氏度，长期存放可置于更低温度。应避免反复冻融，并尽量减少容器开启次数。